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• How to record a 5 second video on Raspberry Pi 3 with USB webcam ?

  16 mars 2023, par Feengineer

  Hi i tried to record a video whit a USB-webcam on my RaspberryPi.
When i type ffplay /dev/video0 I do see a live video, but when i try to record it with ffmpeg the video output is like a black screen with like the traffic cone in my VLC media player. I tried saving the video as a .mkv and .mp4 file. Anyone know how to fix this ?

  


  The code i used to record a video is : ffmpeg -f v4l2 -t 5 -framerate 25 -video_size 640x480 -i /dev/video0 output.mkv and ffmpeg -f v4l2 -t 5 -framerate 25 -video_size 640x480 -i /dev/video0 output.mp4
The video did show up in the folder, but it doesn't show video when opening.

  


  edit : I fixed it now by changing the file type to .avi, but if anyone can still explain how to get .mkv or .mp4, let me know :)

  


• Process Multiple Streams using ffmpeg-python

  27 novembre 2019, par C Dorman

  I have a MPEG-2 TS with a stream of video and a steam of KLV metadata. I can use ffmpeg-python to process each of these streams independently. For example, I can get the video stream, process each frames using numpy as shown in the docs. I can also get the data stream and show it in following way (using the library klvdata) :

  process = (
  
      ffmpeg
  
          .input(in_filename)
  
          .output('pipe:', format='data', codec='copy', map='data-re')
  
          .run_async(pipe_stdout=True, pipe_stderr=True)
  
  )
  
  
  
  for packet in klvdata.StreamParser(process.stdout.read()):
  
      packet.structure()
  
  
  
  process.wait()

  How do I do these at the same time ? I need to split the TS data into its streams and process them both, keeping them in sync. ffmpeg by itself can demultiplex the streams into separate files, but how do I handle the streams in python. The KLV has information that I want to show on top of the video stream (recognition boxes).

• How to create UI for Terminal [y/n] Prompts ?

  22 juin 2023, par itsRits

  I am working with FFmpeg and I want to create a responsive user interface for terminal prompts.

  


  Here's the main function.

  


  #converter.py

def convert_video(input_video, output_video=None, new_fps=None, new_container=None):

   if not output_video:
      if new_container is not None:
         output_video = "output." + new_container
      else:
         output_video = "output." + input_video.split('.')[-1]
   
   command = f"ffmpeg -i {input_video}"

   if new_fps:
      command += f' -r {new_fps}'

   command += f' {output_video}'

   subprocess.call(command, shell=True)


  


  On running the above code, if the video at the output destination with the same name already exists.
the terminal prompts :File 'output.mp4' already exists. Overwrite? [y/N].
I want to implement same using the message box in pyside2. I can create a message box in such a fashion

  


  #ui.py
    message_box = QMessageBox()
    message_box.setText("Do you want to proceed?")
    message_box.setStandardButtons(QMessageBox.Yes | QMessageBox.No)
    message_box.setDefaultButton(QMessageBox.No)


  


  But I am unable to figure how to make the message box pop once this prompt is found in terminal. Further how to send response back to it ?